I don't use any and never have and I don't have loaded tires either. I do have cast centers on both tractors however. Most loaders today can and will overpower the tractor they are mounted on anyway so I use the tractor as my 'yardstick' as to what I can pick up and what I cannot.
Do keep one thing in mind and that is, unless you move into the 100 plus horsepower range, your tractor most likely has ball bearings in the outboards instead of tapered roller bearings that are in larger units and those ball bearings don't like to be overloaded and will eventually fail from that overload condition.
Rear ballast is nothing more than a band aid to cause you to overload the front end and those ball bearings in your front axle don't like to be overloaded and to a lesser extent, neither do the front tires and rims.
Your unit but expect failure from overloading at some point in the future.
I have 6000 hours on one of mine and never had an issue but I don't overload it either.